Key facts

Key Facts

The Dam

  • The dam is 53 metres high and 220 metres long.
  • It’s constructed from 490,000 cubic metres of rock, 32,000 cubic metres of concrete, and more than 3,000 tonnes of reinforcing steel.
  • 110,000 cubic metres of drainage rock and 25,000 tonnes of sand were imported to the site for use in construction.
  • 17,000 metres of drilling was needed for the waterproof grouting around the dam.
  • The concrete face of the dam by itself is 12,000 square metres, and it needed 4,000 cubic metres of concrete to be produced. An on-site concrete batching plant was set up to make this concrete – turning what would have been a one-hour drive for a concrete driver into just five minutes. To construct the longest concrete slab on the concrete face, the concrete slipforming had to run continuously for 50 hours!

The Spillway

  • The spillway is 165 metres long.
  • It has a 158-metre-long reinforced concrete channel for water to flow down when the reservoir is full. It can handle 1,058m3 per second (which is like pouring an Olympic-sized swimming pool into the chute every two seconds).

The Diversion Culvert

  • The diversion culvert is 165 metres long, 7 metres wide and 5.6 metres high.
  • It is made of 4,500 cubic metres of concrete and 815 tonnes of steel.
  • Inside the culvert is 160 metres of pipework.
  • It is designed to pass a 1-in-1,000-year-flood.

Economic Benefit

  • At its construction peak, there were approximately 150 predominantly local people employed onsite each day.
  • The estimated economic benefit in the first two years is $55 million, and between $600-$900 million over 25 years (NZIER report).


  • On Rough Island, Waimea Water Ltd planted 40,000 trees over a 3-year period.
  • 10,000 plants were planted at the 10 HA Waimea Bermlands as the start of a future native forest.
  • A large 3.8 – 5.0 hectares of native beech forest planting has been undertaken at the dam site.